How salts affect the rheological behavior of an aluminum titanate-based ceramic paste

Abstract

This article describes how eight different salts impact the rheological behavior of an aluminum titanate-based ceramic paste. A capillary rheometer was used to measure the thermal phase transition temperature of a hydroxypropyl methylcellose binder in the paste. The transition of the binder causes the paste to increase in viscosity and the temperature at which this occurs is defined as the stiffening onset temperature (T onset). The T onset was found to be a linear function of salt concentration and the slope of this relationship is called the salt strength. Four of the five salts behaved as "salt-out" salts and depressed T onset while three showed "salt-in" behavior and raised T onset. The salt strength occurred in a regular order based on the anion type consistent with the Hofmeister series. In addition, the specific mixing energy of the paste during plasticization was also affected by the ion type present in the batch and was consistent with the Hofmeister series. The results show how the presence of salts can influence the interaction between the binder and water in a highly filled system and illustrate how this interaction can impact batch thermorheological behavior of ceramic pastes during the forming process. © 2011 The American Ceramic Society.